1. Field of the Invention
The present invention relates generally to a disk apparatus, and more particularly to a floppy disk apparatus for writing data to and reading data from a rotating floppy disk by movement of a head carriage.
2. Description of the Related Art
Conventionally, floppy disk apparatuses are widely used in personal computers as external memory devices. In recent years, in an effort to cope with the coming video age, floppy disk apparatuses have to be developed that greatly expand memory capacity from the current 1.44 MB to 200 MB or more. In order to expand memory capacity to such a large extent, it is necessary to increase the current 300 rpm rotation speed of the floppy disk by 10 times or more and at the same time increase the current track density of 135 tracks per inch (hereinafter tpi) by 10 times or more, to 2,000 to 3,000 tpi. In order to reliably write and read data under these high-speed, high-density conditions, a high degree of precision is required of the drive of the head carriage of the floppy disk apparatus so as to position the magnetic heads of the head carriage with a high degree of precision. Additionally, the floppy disk apparatus must be slim because it is included within the personal computer apparatus.
FIG. 8(A) and FIG. 8(B) show a head carriage drive mechanism 10 for a conventional high-density floppy disk device. The head carriage drive mechanism 10 has a head carriage 11. The head carriage 11 has a head 12 and is moved and positioned longitudinally in the Y1-Y2 direction along a radius of a rotating floppy disk 17 by a first voice coil motor 13 and a second voice coil motor 14 (hereinafter referred to collectively as first and second voice coil motors 13, 14) provided on either side of the head carriage 11 while being supported by guide rods 15 and 16. The first voice coil motor 13 comprises a magnetic circuit structure 23 including a permanent magnet 20 and yokes 21 and 22, and a drive coil 24 fitted to yoke 22 and fixedly mounted on the head carriage 11. The second voice coil motor 14 comprises a magnetic circuit structure 33 including a permanent magnet 30 and yokes 31 and 32, and a drive coil 34 fitted to yoke 32 and fixedly mounted on the head carriage 11.
As shown in FIG. 8(C), the drive coil 24 and drive coil 34 are connected in series to a power source 40. The first and second voice coil motors 13, 14 generate identical propulsive forces and the head carriage 11 is moved in the Y1-Y2 direction with precision.
When the first and second voice coil motors 13, 14 generate identical propulsive forces and the drive coil 24 and drive coil 34 are connected in series to the power source 40, a number of turns in drive coil 24 and a number of turns in drive coil 34 are identical. As a result, it is difficult to create a space for including a head carriage position detecting mechanism that uses an encoder scale.
Moreover, it is difficult to independently set the propulsive forces of the first and second voice coil motors 13, 14 because drive coil 24 and drive coil 34 are connected in series to the power source 40, thus limiting the freedom with which the head carriage drive mechanism can be designed.
Accordingly, it is an object of the present invention to provide a disk apparatus in which the problems described above are eliminated.
The above-described object of the present invention is achieved by a disk apparatus comprising:
a frame;
disk rotating means for supportably rotating a floppy disk;
a head for writing data to and reading data from a disk being rotated by said disk rotating means;
a head carriage for holding said head, said head carriage being movable in a direction of a radius of a disk supported by said disk rotating means; and
a first voice coil motor and a second voice coil motor for moving said head carriage provided on both sides of said head carriage, said first voice coil motor and second voice coil motor each respectively comprising:
a magnetic circuit structure mounted on said frame; and
drive coils mounted on said head carriage,
wherein said first voice coil motor and second voice coil motor are connected in parallel to an electric power source.
According to the above-described disk apparatus, it is possible to make the first voice coil motor and the second voice coil motor each generate an identical propulsive force even when the drive coil of the first voice coil motor and the drive coil of the second voice coil motor each have a different number of turns. Additionally, by connecting in series a resistor to one of either the first drive coil or the second drive coil it is also possible to make the first voice coil motor and the second voice coil motor each generate a slightly different propulsive force even when the drive coil of the first voice coil motor and the drive coil of the second voice coil motor have an identical number of turns.
As a result, it is possible to create a space for accommodating a head carriage position detecting mechanism that uses an encoder scale, thus expanding the freedom with which the head carriage drive mechanism can be designed.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.